K&N air filter

keith_king

Im currently running a K&N filter , this is the only filter i have ran other than the stock filter. has anyone else ran K&N and if so is there a better filter or is this one getting the job done? thanks ahead of time keith

Tony_Miller

Well, I have a K&N filter on my WR400, and, I will say it does run very well with it, definitely better than with a UNI, at least with my jetting, however, I would not even think of using the K&N without a foam prefilter, beause it does pass more fine dust than a foam filter. K&N doesn't make a premade prefilter for the WR, so I bought the bulk foam and fashioned my own using a hot glue gun. Then I added a retainer to hold the prefilter in place. With the prefilter oiled with foam filter oil, I'm satisfied with the level of filtration. (Do not use the K&N oil on foam, it's too runny.) If your interested, I could get some photos of my mods.

Dean400

I have a K&N filter on my '98 WR 400. It came with a pre-filter outerwear made by the same company that makes their pre-chargers. I got it through Rocky Mountain mc. But, I think you have to buy the filter and the outerwear as a package deal.

One thing I noticed was, when I switched to the K&N air filter, the motor did not seem to lug as well. For example, going up a long steep sand hill, with the stock filter on, the bike would be able to lug to a very low R.P.M. With the K&N on, in simmilar situations, the motor would stall before reaching low R.P.M. Has anyone else noticed this?

TeamScream

Thats because it may be getting more air then it was stock or with your uni filter...you may need to richen it up a bit all the way around to cure that problem, I run a K&N and it runs very well, but since my bike sees NO dirt I do not run a pre filter, I believe that the pre filters detract from the overall purpose of the K&N, in fact K&N suggests that you do NOT clean the filter that often, because the fine dust that is trapped by the oil on the outer screen and gauze inner actually improves filtration while not decreasing airflow. if you doubt this read the info on K&N's website....its good reading actually

Tony_Miller

TeamScream, a dirtbike that sees no dirt? How do you manage that? Dean400, is that prefilter a foam type or a nylon mesh type? As far as the prefilter taking away the benefit of the K&N, it doesn't, or at least it is so slight it is not noticable. The foam is really coarse, but even so it is supposed to stop like 90% of the dirt. It is really easy to clean the foam, and I have never cleaned the K&N yet. Just don't use the K&N oil on the foam, it doesn't work well at all.